QoS Challenges and Opportunities in Wireless Sensor/Actuator Networks

A wireless sensor/actuator network (WSAN) is a group of sensors and actuators that are geographically distributed and interconnected by wireless networks. Sensors gather information about the state of physical world. Actuators react to this information by performing appropriate actions. WSANs thus enable cyber systems to monitor and manipulate the behavior of the physical world. WSANs are growing at a tremendous pace, just like the exploding evolution of Internet. Supporting quality of service (QoS) will be of critical importance for pervasive WSANs that serve as the network infrastructure of diverse applications. To spark new research and development interests in this field, this paper examines and discusses the requirements, critical challenges, and open research issues on QoS management in WSANs. A brief overview of recent progress is given.Comment: 12 pages, 1 figure; revie

MFACE: A Multicast Backbone-Assisted Face Traversal Algorithm for Arbitrary Planar Ad Hoc and Sensor Network Topologies

Face is a well-known localized routing protocol for ad hoc and sensor networks which guarantees delivery of the message as long as a path exists between the source and the destination. This is achieved by employing a left/right hand rule to route the message along the faces of a planar topology. Although face was developed for the unicast case, it has recently been used in combination with multicasting protocols, where there are multiple destinations. Some of the proposed solutions handle each destination separately and lead thus to increased energy consumption. Extensions of face recovery to the multicast case described so far are either limited to certain planar graphs or do not provide delivery guarantees. A recently described scheme employs multicast face recovery based on a so called multicast backbone. A multicast backbone is a Euclidean spanning tree which contains at least the source and the destination nodes. The idea of backbone assisted routing it to follow the edges of the backbone in order to deliver a multicast message to all spanned destination nodes. The existing backbone face routing scheme is however limited to a certain planar graph type and a certain backbone construction. One of the key aspects of the multicast face algorithm MFACE we propose in this work is that it may be applied on top of any planar topology. Moreover, our solution may be used as a generic framework since it is able to work with any arbitrary multicast backbone. In MFACE, any edge of the backbone originated at the source node will generate a new copy of the message which will be routed toward the set of destination nodes spanned by the corresponding edge. Whenever the message arrives at a face edge intersected by a backbone edge different from the initial edge, the message is split into two copies, both handling a disjoint subset of the multicast destinations which are defined by splitting the multicast backbone at that intersection point

Energy-efficient geographic multicast routing for sensor and actuator networks

Abstract — Most usage scenarios for ad hoc and wireless sensor networks (WSN) require some degree of one-to-many or manyto-many interactions. In particular, for the case of WSN there is a number of scenarios in which a node has to send the same data to multiple destinations. Given that sensor networks have very limited resources, multicasting is a very interesting approach to deliver the same data packet to multiple destinations while reducing the amount of bandwidth and power consumption. Furthermore, recent studies have shown that it is of paramount importance to take into account the error prune nature of the wireless links when designing energy-efficient routing protocols. In this paper, we extend our previously proposed protocol LEMA (Localized Energy-Efficient Multicast Algorithm), to deal with the problems of the error prone WSN. Our simulation results show that for networks with enough density the protocol is abl

Energy Efficient Geographic Multicast Routing for Sensor and Actuator Networks

The case in which the same information or events need to be sent from a single sensor node to multiple actuator nodes, is very common in many applications of Sensor and Actuators Networks (SANET). Sensors have very limited resources in terms of energy, bandwidth and computational power. Thus, routing messages preserving energy and network bandwidth is a challenging requirement of paramount importance. In this paper we present a novel energy-efficient multicast routing protocol called GMREE which is specifically designed to achieve that goal. Our protocol builds multicast trees based on a greedy algorithm using local information. The heuristic we use is based in the concept of cost over progress metric and it is specially designed to minimize the total energy used by the multicast tree. GM-REE incorporates a relay selection function which selects nodes from a node’s neighborhood taking into account not only the minimization of the energy but also the number of relays selected. Nodes only select relays based on a locally-built and energy-efficient underlying graph reduction such as Gabriel graph, enclosure graph or a local shortest path tree. Thus the topology of the resulting multicast trees really takes advantage of the benefit of sending a single message to multiple destinations through the relays which provide best energy paths. Our simulation results show that our proposed protocol outperforms the traditional energy-efficient multiunicast routing over a variety of network densities and number of receivers. In addition, for dense networks, the performance approximates the one achieved using the centralized shortest weighted path tree (computed by Dijkstra’s algorithm). 1

A middleware framework for wireless sensor network

Advances in wireless and Micro-Electro-Mechanical Systems (MEMS) technology has given birth to a new technology field sensor networks. These new technologies along with pervasive computing have made the dream of a smart environment come true. Sensors being small and capable of sensing, processing and communicating data has opened a whole new era of applications from medicine to military and from indoors to outdoors. Sensor networks although exciting have very limited resources, for example, memory, processing power and bandwidth, with energy being the most precious resource as they are battery operated. However, these amazing devices can collaborate in order to perform a task. Due to these limitations and specific characteristics being application specific and heterogeneous there is a need to devise techniques and software which would utilize the meager resources efficiently keeping in view the unique characteristics of this network. This thesis presents a lightweight, flexible and energy-efficient middleware framework called MidWSeN which combines aspects of queries, events and context of WSN in a single system. It provides a combination of core and optional services which could be adjusted according to the resources available and specific requirements of the application. The availability of multiple copies of services distributed across the network helps in making the system robust. This middleware framework introduces a new Persistent Storage Service which saves data within the sensor network on the nodes for lifetime of the network to provide historical data. A Priority algorithm is being also presented in this thesis to ensure that enough memory is always available. A novel context enhanced aggregation has also been presented in this thesis which aggregates data with respect to context. Application management service (AMS) provides Service optimization within the network is another novel aspect of the proposed framework. To evaluate the functionality of the work presented, different parts of the framework have also been implemented. The tests and results are detailed to prove the ideas presented in the framework. The work has also been evaluated against a set of requirements and compared against existing works to indicate the novel aspects of framework. Finally some ideas are presented for the future works